Tweaking a CNN for large number of input channels
As far as I know, more than 3 channel is perfectly fine, since, 3 channels are what we use for images and that's enough since we can only see this many colors, but I don't see why more than that wouldn't work

Your 2nd question is like asking whether or not you will be good at a sport... Just try it

For your 3rd question, I've never seen any language AI using CNN instead they all use RNN, not sure if that's what you meant though